1. Field of the Invention
The present invention relates to apparatus and methods for the treatment of coal fines, and more particularly to a method and apparatus for separating clay particles from the other particles present in coal fines. The present invention further relates to the agglomeration of coal particles, and the pre-treatment of such particles for that process.
2. Description of the Prior Art
Various apparatus and methods are known in the prior art for treating coal fines or other mixtures including coal particles. In general, these prior art methods and apparatus are directed to separating and/or washing of the material, in contrast to the present invention which has the particular purpose of removing the clay particles from the coal mixture.
In U.S. Pat. No. 2,196,451, issued to Holzer on Apr. 9, 1940, there is shown a method and apparatus for separating, washing and grading lump material. The apparatus of the Holzer patent includes a verticle tower into which the lump material is delivered. The tower provides a head of the material to force the material from the bottom of the tower into the remaining portion of the apparatus. The apparatus is filled with a liquid medium which has a greater specific gravity than the coal or other lump material to cause such material to float in the liquid medium. The floating material is moved along an open mesh and permitted to pass therethrough in a grading operation, while heavier materials settle onto a belt conveyor for removal. The Holzer apparatus and method utilize the special medium to provide for floating of the coal particles, and further uses dry or as-received coal which is introduced into the hopper below the fluid level. In contrast, the present invention utilizes a water suspension of coal fines, typically fourteen mesh or smaller, which aqueous solution is introduced into the hopper above the fluid level. The Holzer apparatus specifically provides for maintaining the medium in agitation. The present invention is specifically intended to provide for the water in the hopper remaining very calm to permit the separation of the clay particles from the heavier than water particles.
A typical mechanical classifier is disclosed in U.S. Pat. No. 1,306,188, issued to Marcy on June 10, 1919. In accordance with the Marcy patent, the crushed ore or other material is delivered into the hopper below the liquid level and mixers operate to provide constant agitation within the hopper. A chain driven conveyor is provided for removing the settled particles. In contrast to the Marcy apparatus and method, the present invention separates the clay particles from the other components of coal fines by permitting the clay to remain suspended in the water and be removed with the overflow from the hopper.
The particular features of the present apparatus and method provide for simple, inexpensive and efficient separation of clay particles from the other components of coal fines. The present invention is particularly useful in connection with a coal agglomeration process, the clay particles desirably being removed to prevent their interference with the agglomeration process.